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Knowledge of anatomy is essential to the understanding of disease and conditions of the oral cavity and salivary glands. This article is intended to serve as an overview of the oral cavity, its subsites, and that of the neighboring salivary glands. The authors cover the anatomy of the lips, tongue, floor of mouth, hard palate, teeth, various mucosal areas, and salivary ducts. When appropriate, radiological imaging along with figures serves as a companion to highlight the clinical relevance and practical applications of specific anatomic locations.

This study aimed to quantify the adenoidal-nasopharyngeal ratio (ANR) in a cohort of healthy adults on cone beam computed tomography (CT) using the Fujioka method, which is a reproducible measure of adenoid size and nasopharyngeal patency.Electronic health records and maxillofacial cone beam CT in 202 consecutive patients aged 16 years and older were retrospectively reviewed. Patients with a history of adenoidectomy, sinonasal disease, lymphoproliferative disorders, and cleft palate were excluded from the study. The midsagittal reconstructed cone beam CT image was used to determine the ANR. Statistical analysis was conducted using 1-way analysis of variance.Of the 202 subjects, 131 were female and 71 were male. The mean ± SD subject age was 45.43 ± 20.79 years (range, 16-91 years). The mean ± SD ANR in all subjects was 0.22 ± 0.13 (range, 0.03-0.75) and in each decade of adult life was as follows: younger than 21 years, 0.39 ± 0.12; 21 to 30 years, 0.29 ± 0.11; 31 to 40 years, 0.21 ± 0.09; 41 to 50 years, 0.20 ± 0.07; 51 to 60 years, 0.16 ± 0.10; 61 to 70 years, 0.13 ± 0.05; 71 to 80 years, 0.12 ± 0.05; 81 to 90 years, 0.11 ± 0.04; and 91 years or older, 0.10 ± 0. The differences in mean ANR among the age subgroups were statistically significant ( P0.001).The mean ANR gradually decreased from 0.39 in the second decade of life to 0.16 in the sixth decade of life and plateaued at approximately 0.10 thereafter.

This article discusses mimics, anatomic variants, and pitfalls of imaging of the sinonasal cavity, orbit, and jaw. The authors discuss clinical findings and imaging pearls, which help in differentiating these from one another.

The use of standardized imaging protocols is paramount in order to facilitate comparable, reproducible images and, consequently, to optimize patient care. Standardized MR protocols are lacking when studying head and neck pathologies in the pediatric population. We propose an international, multicenter consensus paper focused on providing the best combination of acquisition time/technical requirements and image quality. Distinct protocols for different regions of the head and neck and, in some cases, for specific pathologies or clinical indications are recommended. This white paper is endorsed by several international scientific societies and it is the result of discussion, in consensus, among experts in pediatric head and neck imaging.

Hyperparathyroidism is defined as excessive parathyroid hormone production. The diagnosis is made through biochemical testing, in which imaging has no role. However, imaging is appropriate for preoperative parathyroid gland localization with the intent of surgical cure. Imaging is particularly useful in the setting of primary hyperparathyroidism whereby accurate localization of a single parathyroid adenoma can facilitate minimally invasive parathyroidectomy. Imaging can also be useful to localize ectopic or supernumerary parathyroid glands and detail anatomy, which may impact surgery. This document summarizes the literature and provides imaging recommendations for hyperparathyroidism including primary hyperparathyroidism, recurrent or persistent primary hyperparathyroidism after parathyroid surgery, secondary hyperparathyroidism, and tertiary hyperparathyroidism. Recommendations include ultrasound, CT neck without and with contrast, and nuclear medicine parathyroid scans. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Sinonasal cavity is an important subsite in head and neck tumors. There are a myriad of malignancies that present within this area. Adequate staging for treatment planning requires multimodality evaluation. Magnetic resonance imaging (MRI) forms an important component in the evaluation of sinonasal tumors. We sought to review the most common sinonasal tumors, including sinonasal anatomy, clinical features, and common imaging features. A literature review was performed to evaluate common sinonasal tumors. Owing to the different tissue types within the sinonasal cavity, there are multiple different tumor pathologies within the sinonasal compartment. Most present in adults although some present in the young. Many of these tumor types have imaging overlaps, although some have a characteristic appearance. MRI can aid in soft tissue delineation, evaluation of multicompartmental extension, intracranial spread, and perineural spread. Sinonasal tumors are a heterogeneous group for which soft tissue delineation via MRI forms an important role in ensuring adequate treatment planning to improve outcomes, decreasing morbidity, and improve functional outcomes.

A posterior skull base lesion is an uncommon radiological finding that may be noted incidentally or during targeted imaging of patients with clinical symptoms attributable to the lesion. It may be inflammatory or neoplastic in etiology, or may simply be an anatomic variant or a "don't-touch" lesion that should not be misinterpreted as something more ominous. A systematic approach to the evaluation of the posterior skull base is therefore required in order to differentiate lesions requiring immediate attention from those requiring a less urgent course of action or none at all. This review will focus on the imaging features of pathologic conditions that are more commonly encountered in posterior skull base CT and MR examinations.

Degenerative disease of the central nervous system is a growing public health concern. The primary role of neuroimaging in the workup of patients with probable or possible Alzheimer disease has typically been to exclude other significant intracranial abnormalities. In general, the imaging findings in structural studies, such as MRI, are nonspecific and have limited potential in differentiating different types of dementia. Advanced imaging methods are not routinely used in community or general practices for the diagnosis or differentiation of forms of dementia. Nonetheless, in patients who have been evaluated by a dementia expert, FDG-PET helps to distinguish Alzheimer disease from frontotemporal dementia. In patients with suspected dementia with Lewy bodies, functional imaging of the dopamine transporter (ioflupane) using SPECT may be helpful. In patients with suspected normal-pressure hydrocephalus, DTPA cisternography and HMPAO SPECT/CT brain may provide assessment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Ataxia can result from an abnormality in the cerebellum, spinal cord, peripheral nerves, and/or vestibular system. Pathology involving the brain, such as infarct or hydrocephalus, can also present with ataxia as part of the symptom constitution, or result in symptoms that mimic ataxia. Clinical evaluation by history and careful neurological examination is important to help with lesion localization, and helps determine where imaging should be focused. In the setting of trauma with the area of suspicion in the brain, a head CT without intravenous contrast is the preferred initial imaging choice. If vascular injury is suspected, CTA of the neck can be helpful. When the area of suspicion is in the spine, CT or MRI of the spine can be considered to assess for bony or soft-tissue injury, respectively. In the setting of ataxia unrelated to recent trauma, MRI is the preferred imaging modality, tailored to assess the brain or spine depending on the area of suspected pathology. The use of intravenous contrast is generally helpful. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Neuroendocrine dysfunction includes suspected hyper- and hypofunction of the pituitary gland. Causative lesions may include primary masses of the pituitary such as pituitary microadenomas and macroadenomas, as well as extrinsic masses, typically centered in the suprasellar cistern. Clinical syndromes related to hormonal dysfunction can be caused by excessive hormonal secretion or by inhibited secretion due to mass effect upon elements of the hypothalamic-pituitary axis. Additionally, complications such as hemorrhage may be seen in the setting of an underlying mass and can result in hormonal dysfunction. MRI with high-resolution protocols is the best first-line test to evaluate the sella turcica and parasellar region. CT provides complementary information regarding bony anatomy, and may be appropriate as a first-line test in certain instances, but it provides less detail and lesion characterization when compared to MRI. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Deep learning with convolutional neural networks (CNNs) has experienced tremendous growth in multiple healthcare applications and has been shown to have high accuracy in semantic segmentation of medical (e.g., radiology and pathology) images. However, a key barrier in the required training of CNNs is obtaining large-scale and precisely annotated imaging data. We sought to address the lack of annotated data with eye tracking technology. As a proof of principle, our hypothesis was that segmentation masks generated with the help of eye tracking (ET) would be very similar to those rendered by hand annotation (HA). Additionally, our goal was to show that a CNN trained on ET masks would be equivalent to one trained on HA masks, the latter being the current standard approach. Step 1: Screen captures of 19 publicly available radiologic images of assorted structures within various modalities were analyzed. ET and HA masks for all regions of interest (ROIs) were generated from these image datasets. Step 2: Utilizing a similar approach, ET and HA masks for 356 publicly available T1-weighted postcontrast meningioma images were generated. Three hundred six of these image + mask pairs were used to train a CNN with U-net-based architecture. The remaining 50 images were used as the independent test set. Step 1: ET and HA masks for the nonneurological images had an average Dice similarity coefficient (DSC) of 0.86 between each other. Step 2: Meningioma ET and HA masks had an average DSC of 0.85 between each other. After separate training using both approaches, the ET approach performed virtually identically to HA on the test set of 50 images. The former had an area under the curve (AUC) of 0.88, while the latter had AUC of 0.87. ET and HA predictions had trimmed mean DSCs compared to the original HA maps of 0.73 and 0.74, respectively. These trimmed DSCs between ET and HA were found to be statistically equivalent with a p value of 0.015. We have demonstrated that ET can create segmentation masks suitable for deep learning semantic segmentation. Future work will integrate ET to produce masks in a faster, more natural manner that distracts less from typical radiology clinical workflow.

There are a wide variety of diseases that affect the thyroid gland ranging from hyperplastic to neoplastic, autoimmune, or inflammatory. They can present with functional abnormality or a palpable structural change. Imaging has a key role in diagnosing and characterizing the thyroid finding for management. Imaging is also essential in the management of thyroid cancer. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

This section aims to cover the non-traumatic pathologies affecting the temporal bone including external auditory canal, middle ear and inner ear which usually need emergent clinical attention. Many of the conditions in this section are secondary to infections in different clinical settings with resultant complications which may leave temporary or permanent sequelae if not suspected, timely diagnosed or treated.

The differential diagnosis of a red and/or pulsatile retrotympanic mass includes aberrant internal carotid artery, persistent stapedial artery (PSA), glomus tympanicum, and dehiscent jugular bulb. By recognizing the features of aberrant internal carotid artery and PSA on high-resolution computed tomography, these entities can be assessed by the radiologist. PSA is further classified by type because each type demonstrates a unique set of imaging features in addition to features common to all types. Although rarely encountered, it is important to reliably and consistently detect these anomalies because failure to do so can lead to disastrous surgical outcomes.

Neurologic involvement is well-recognized in COVID-19. This article reviews the neuroimaging manifestations of COVID-19 on CT and MRI, presenting cases from the New York City metropolitan region encountered by the authors during the first surge of the pandemic. The most common neuroimaging manifestations are acute infarcts with large clot burden and intracranial hemorrhage, including microhemorrhages. However, a wide range of additional imaging patterns occur, including leukoencephalopathy, global hypoxic injury, acute disseminated encephalomyelitis, cytotoxic lesions of the corpus callosum, olfactory bulb involvement, cranial nerve enhancement, and Guillain-Barre syndrome. The described CNS abnormalities largely represent secondary involvement from immune activation that leads to a prothrombotic state and cytokine storm; evidence for direct neuroinvasion is scant. Comorbidities such as hypertension, complications of prolonged illness and hospitalization, and associated supportive treatments also contribute to the CNS involvement in COVID-19. Routine long-term neurologic follow-up may be warranted, given emerging evidence of long-term microstructural and functional changes on brain imaging after COVID-19 recovery.

Even though teeth are often included in the field of view for a variety of medical CT studies, dental pathology is often missed by radiologists. Given the myriad morbidity and occasional mortality associated with sequelae of dental pathology, an important goal is to decrease these false negatives. However, given the ever-increasing volume of cases studies that radiologists have to read and the number of structures and diseases they have to evaluate, it is important not to place undue time restraints on the radiologist to this end. We hypothesized that generating panoramic dental radiographs from non-dental CT scans can permit identification of key diseases, while not adding much time to interpretation. The key advantage of panoramic dental radiographs is that they display the plane of the teeth in two dimensions, thereby facilitating fast and accurate assessment. We found that interpreting panoramic radiographic reconstructions compared to the full CT volumes reduced time-to-diagnosis of key dental pathology on average by roughly a factor of four. This expedition was statistically significant, and the average time-to-diagnosis for panoramic reconstructions was on the order of seconds, without a loss in accuracy compared to full CT. As such, we posit that panoramic reconstruction can serve as a one-slice additional series in any CT image stack that includes the teeth in its field of view.

Objective FSE sequences play key roles in neck MRI despite the susceptibility issues in neck region. Iterative decomposition of asymmetric echoes (IDEAL, GE) is a promising method that separates fat and water images resulting in high SNR and improved fat suppression. We tested how neck tissue contrasts, image artifacts and fat separation as opposed to fat suppression in terms of image quality compare between routine and IDEAL FSE. Methods IDEAL based and routine T1 and T2-weighted FSE sequences were applied for neck MRI at 1.5T and 3T. Overall image quality including fat suppression, tissue contrast, image artifacts and lesion conspicuity were subjectively assessed for 20 patients clinically indicated for neck MRI. Quantitative tissue contrast estimates from parotid area were compared between IDEAL and routine FSE for 7 patients. Four patients with oncocytoma were also reviewed to assess benefits of separately reconstructed fat specific image sets. Results Subjective tissue contrast and overall image quality including image sharpness, fat suppression and image artifacts were superior for IDEAL sequences. For oncocytoma fat specific IDEAL images provided additional information. Objective CNR estimates from a central slice were equivalent for IDEAL and routine FSE at both field strengths. Conclusions We demonstrated that high SNR inherent in IDEAL FSE consistently translates into high tissue contrast with image quality advantages in neck anatomy where large susceptibility variation and physiological motions reduce image quality for conventional FSE T1 and T2. However, the objective contrast estimates for parotid gland at isocenter were statistically equivalent for IDEAL and conventional FSE perhaps because at or near isocenter routine FSE works well. Additionally, fat specific IDEAL image sets add to diagnostic specificity for fat deficient lesions.

Visual loss can be the result of an abnormality anywhere along the visual pathway including the globe, optic nerve, optic chiasm, optic tract, thalamus, optic radiations or primary visual cortex. Appropriate imaging analysis of visual loss is facilitated by a compartmental approach that establishes a differential diagnosis on the basis of suspected lesion location and specific clinical features. CT and MRI are the primary imaging modalities used to evaluate patients with visual loss and are often complementary in evaluating these patients. One modality may be preferred over the other depending on the specific clinical scenario. Depending on the pattern of visual loss and differential diagnosis, imaging coverage may require targeted evaluation of the orbits and/or assessment of the brain. Contrast is preferred when masses and inflammatory processes are differential considerations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

This article provides a practical overview of head and neck cancers, outlining an approach to evaluating these lesions and optimizing imaging strategies. Recognition of key anatomic landmarks as suggested by American Joint Committee on Cancer (AJCC) tumor, node, metastasis (TNM) criteria is emphasized. Further, the recently updated eighth edition of the AJCC staging manual has introduced some modifications that influence the TNM staging. These modifications are discussed throughout the article to provide an updated review on head and neck cancer.

Evaluation of cranial neuropathy can be complex given the different pathway of each cranial nerve as well as the associated anatomic landmarks. Radiological evaluation requires imaging of the entire course of the nerve from its nucleus to the end organ. MRI is the modality of choice with CT playing a complementary role, particularly in the evaluation of the bone anatomy. Since neoplastic and inflammatory lesions are prevalent on the differential diagnosis, contrast enhanced studies are preferred when possible. The American College of Radiology Appropriateness Criteria are evidencebased guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Non-traumatic orbital pathology can often have overlapping imaging features and challenging timely diagnosis. Prompt recognition is necessary due to potential risk of permanent visual loss. In this article we present systematic evaluation of non-traumatic orbital pathology with attention to key imaging features, pathogenesis and potential complications.

A growing body of evidence has shown that a relationship between age-related hearing loss and structural brain changes exists. However, a method to measure brain atrophy associated with hearing loss from a single MRI study (i.e. without an interval study) that produces an independently interpretable output does not. Such a method would be beneficial for studying patterns of structural brain changes on a large scale. Here, we introduce our method for this. Audiometric evaluations and mini-mental state exams were obtained in 34 subjects over the age of 80 who have had brain MRIs in the past 6 years. CSF and parenchymal brain volumes (whole brain and by lobe) were obtained through a novel, fully automated algorithm. Atrophy was calculated by taking the ratio of CSF to parenchyma. High frequency hearing loss was associated with disproportional temporal lobe atrophy relative to whole brain atrophy independent of age (r = 0.471, p = 0.005). Mental state was associated with frontoparietal atrophy but not to temporal lobe atrophy, which is consistent with known results. Our method demonstrates that hearing loss is associated with temporal lobe atrophy and generalized whole brain atrophy. Our algorithm is efficient, fully automated, and able to detect significant associations in a small cohort., Highlights • A novel, fully automated method measuring brain atrophy using CSF to brain parenchymal volume ratios is introduced. • Brain atrophy is obtained from a single MRI study and unlike brain volume, is interpretable without relative comparison. • Age-related hearing loss is significantly associated with both temporal lobe and generalized whole brain atrophy.

Temporal bone pathologies are challenging to discern because of their small size and subtle contrast. MR imaging is one of the key modalities in evaluating otologic diseases. Current advancement in MR techniques provide multiparametric information for evaluation of these pathologies. The aim of this article is to review state-of-the-art 3-dimensional morphologic and diffusion sequences for otologic MR imaging.

The first part of this review of the temporal bone discussed anatomy of the temporal bone as well as inflammatory and neoplastic processes in the temporal bone region (1). This second part will first discuss trauma to the temporal bone and posttraumatic complications. The indications for common surgical procedures performed in the temporal bone and their postoperative imaging appearance are then presented. Finally, a few noninflammatory nonneoplastic entities involving the temporal bone are reviewed. They are relatively uncommon diagnoses compared with infectious or inflammatory diseases. However, because patients present with symptoms that are either common (hearing loss) or distinctive (sensorineural hearing loss in a child), they are important for the radiologist to be aware of and recognize.

Clinical Presentation Symptoms of facial nerve palsy depend on the location of injury. The motor nucleus of CN VII has dorsal and ventral divisions that supply the upper and lower face, respectively. There is bilateral innervation of the dorsal division but only contralateral innervation of the ventral division. Supranuclear lesions affect upper motor neurons proximal to the motor nucleus in such locations as the cerebral cortex, internal capsule, and cerebral peduncle. This results in central facial palsy that affects the contralateral lower face but spares the forehead and brow muscles. Infranuclear lesions occur distal to the facial nerve nucleus and produce peripheral facial palsy affecting the ipsilateral upper and lower face. Within the infranuclear pathway, the presence of additional symptoms can help further localize lesions. Involvement of CN VI presents with lateral rectus palsy, or inability to abduct the eye. This suggests a lesion of the facial colliculus in the pons, in which efferent CN VII fibers encircle the CN VI motor nucleus. Involvement of CN VIII causes auditory or vestibular symptoms. This suggests a cisternal or canalicular lesion in which CN VII and VIII nerve roots course together after emerging from the cerebellopontine angle. Finally, certain branches of the facial nerve control specialized functions. The greater superficial petrosal nerve controls lacrimation, the stapedius dampens sound transmission in the inner ear, and the chorda tympani is responsible for taste. Lesions proximal to the geniculate ganglion lose all three functions, lesions between the geniculate ganglion and stylomastoid foramen have preserved lacrimation, and extracranial lesions spare all three functions. Anatomy and Pathology of the Facial Nerve

HistoryA 15-year-old boy presented to the emergency department with intractable epistaxis. He had a prior history of epistaxis typically lasting 5–10 minutes and consisting of up to four episodes per year for several years. Otherwise, the patient had no relevant medical history, and he denied having prior trauma, surgery, bleeding diathesis, fever, chills, or vision changes. Likewise, the patient had no relevant family history. The patient’s coagulation panel was unremarkable and included a prothrombin time of 15.4 seconds, an international normalized ratio of 1.2, and a partial thromboplastin time of 29.3 seconds.A thin-section unenhanced sinus computed tomography (CT) examination was performed. In addition, magnetic resonance (MR) imaging of the sinuses without and with intravenous contrast material was performed.The epistaxis was treated with nasal packing, which prevented further bleeding. Biopsy of the lesion was subsequently performed.

BACKGROUND AND PURPOSE: The lateral rectus–superior rectus band is an orbital connective tissue structure that has been implicated in a form of strabismus termed sagging eye syndrome. Our purpose was to define the normal MR imaging and CT appearance of this band in patients without strabismus. MATERIALS AND METHODS: Orbital MR imaging and CT examinations in 100 consecutive patients without strabismus were evaluated. Readers graded the visibility of the lateral rectus–superior rectus band on coronal T1WI, coronal STIR, and coronal CT images. Readers determined whether the band demonstrated superotemporal bowing or any discontinuities and whether a distinct lateral levator aponeurosis was seen. Reader agreement was assessed by κ coefficients. Association between imaging metrics and patient age/sex was calculated by using the Fisher exact test. RESULTS: The lateral rectus–superior rectus band was visible in 95% of coronal T1WI, 68% of coronal STIR sequences, and 70% of coronal CT scans. Ninety-five percent of these bands were seen as a continuous, arc-like structure extending from the superior rectus/levator palpebrae muscle complex to the lateral rectus muscle; 24% demonstrated superotemporal bowing; and in 82% of orbits, a distinct lateral levator aponeurosis was visible. Increasing patient age was negatively associated with lateral rectus–superior rectus band visibility ( P = .03), positively associated with lateral rectus–superior rectus band superotemporal bowing ( P = .03), and positively associated with lateral levator aponeurosis visibility ( P = .01). CONCLUSIONS: The lateral rectus–superior rectus band is visible in most patients without strabismus on coronal T1WI. The age effect with respect to its visibility and superotemporal bowing could represent age-related connective tissue degeneration.

BACKGROUND AND PURPOSE: An acquired attic cholesteatoma may spontaneously drain externally into the external auditory canal, leaving a cavity in the attic with the shape of the original cholesteatoma but now filled with air, a phenomenon referred to as “nature's atticotomy” or auto-atticotomy. We describe and quantify the CT appearance of the auto-atticotomy cavity as it pertains to the appearance of the scutum and the lateral attic wall. MATERIALS AND METHODS: Twenty-one patients with erosion of the scutum and loss of the lower attic wall on MDCT were identified during a 5-year span. Images were assessed for measureable widening of the space between the ossicles and the lower lateral attic wall in the axial and coronal planes. Three measurements of the lateral attic were made on the axial images. Findings were compared with the same measurements in 20 control subjects. RESULTS: The 21 patients had a characteristic blunting of the scutum with loss of the lower lateral attic wall and widening of the lateral attic, consistent with an auto-atticotomy. There was a statistically significant (P < .001) widening of the lateral attic dimensions in the axial plane in the patients with auto-atticotomy. CONCLUSIONS: Spontaneously evacuated cholesteatoma may mimic a surgical atticotomy on MDCT. Scutal erosion and attic enlargement with a smoothly contoured bony remodeling of the lower lateral attic wall in a patient with no history of surgery suggest that a cholesteatoma was previously present and spontaneously drained.

W371 tory processes tend to have a diffuse pattern, typically involving both the orbital and palpebral lobes of the gland. The palpebral lobe is the portion of the lacrimal gland that is usually visible when the upper eyelid is everted on physical examination. The lacrimal gland normally measures approximately 20 × 12 × 5 mm. Although the size of a normal lacrimal gland may vary from person to person, the glands are usually symmetric, and asymmetry is an important indicator of abnormality. On CT, the lacrimal gland is isodense to the muscle. The medial border is outlined by orbital fat and the lateral border by orbital bone (Fig. 1C). Calcifications and bony changes are well seen on CT (Fig. 2), and normal glands show symmetric contrast enhancement. The superior resolution of MRI permits better assessment of the extent of glandular and periglandular involvement. Normal lacrimal glands have intermediate (sometimes heterogeneous) signal on both T1-weighted and T2weighted imaging and enhance symmetrically after gadolinium administration (Fig. 2).

T his article reviews the causes and imaging appearances of lesions involving the corpus callosum (Table 1). The corpus callosum consists of densely bundled white matter tracts connecting the two cerebral hemispheres, with a compact structure that largely blocks interstitial edema and tumor spread. Isolated lesions of the corpus callosum are rare and may represent transient responses to injury or myelination abnormalities. More common butterfly lesions involve the corpus callosum and both cerebral hemispheres—a pattern associated with aggressive tumors, demyelination, and traumatic brain injury. Unenhanced CT is a first-line neuroimaging modality. Although soft-tissue contrast enhancement is limited, CT can help characterize hemorrhage, edema, mass effect, calcification, and necrosis. MRI provides more detailed information regarding tissue structure and composition, using various pulse excitation sequences, such as FLAIR, to distinguish abnormal signal in the corpus callosum from adjacent CSF in the lateral ventricles. Administration of IV contrast material is useful for characterization of neoplastic and vascular lesions, which may show characteristic patterns of enhancement.

This article discusses the imaging manifestations of infectious and inflammatory conditions of the head and neck. Special attention is paid to the sites, routes of spread, and complications of neck infections. Because the clinical signs and symptoms and the complications of these conditions are often determined by the precise anatomic site involved, anatomic considerations are stressed. Familiarity with the fascial layers, spaces of the neck, and the contents of each space is helpful for this discussion. The fascial layers of the neck are important barriers to infection, and once infection is established, the fascial layers play a part in directing its spread.

A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BA should begin first by studying a series of isolated defects (cleft lip with or without CP, micrognathia, and EAC atresia) that compose the major features of these syndromes and allow a more specific diagnosis. After discussion of these defects and the associated embryology, we discuss PRS, HFM, ACS, TCS, Stickler syndrome, and VCFS.

BACKGROUND AND PURPOSE: Pleomorphic adenoma is the most common parotid neoplasm. It has a relatively high rate of recurrence after surgery. Imaging features of recurrent parotid pleomorphic adenoma have been infrequently reported in the radiology literature. In the present study, we reviewed our institutional experience with imaging of recurrent parotid pleomorphic adenomas. MATERIALS AND METHODS: Retrospective imaging and chart review of 24 patients (9 men, 15 women; age, 29–63 years) with recurrent pleomorphic adenoma of the parotid were performed. Images were reviewed as to the margins, site, multiplicity, signal intensity, and enhancement pattern of the recurrent lesions by 2 neuroradiologists. RESULTS: We found a high incidence of multiple lesions in the operative bed, most of which were extremely bright on T2-weighted images; some of the lesions demonstrated a cystic appearance with peripheral enhancement. We also noted tiny lesions in the subcutaneous fat and in regions distant from the immediate operative bed. CONCLUSION: Although recurrent disease is usually clinically apparent, sometimes prior surgical history is lacking or recurrence may be detected on routine surveillance imaging after initial surgery. The presence of solitary or multiple subcutaneous T2 hyperintense lesions in the operative bed, subcutaneous fat, and/or spaces adjacent to the parotid in patients with prior parotidectomy for pleomorphic adenoma is consistent with the diagnosis of neoplastic recurrence. The radiologist should maintain a high index of suspicion for recurrent pleomorphic adenoma with this characteristic imaging appearance.

The head and neck is a complex anatomical region that can be evaluated using many imaging modalities. It is important to discern normal structures from ones that are affected by disease and to study how these structures change in their morphological and functional properties with aging. Therefore, using magnetic resonance imaging (MRI), we retrospectively evaluated volumes of the parotid glands, submandibular glands, thyroid gland, tongue, soft palate, and lingual tonsils in 64 subjects ages 13 to 81 years. Volume, attenuation (HU), and metabolic activity (maximum SUV) of the parotid, submandibular, and thyroid glands were assessed retrospectively using positron emission tomography/computed tomography (PET/CT) imaging in 35 subjects ages 10 to 76 years. Metabolic activity (maximum SUV) of the parotid, submandibular, and sublingual glands; tongue; adenoids; and tonsils (lingual and palatine) were evaluated retrospectively using PET imaging in 15 subjects ages 6 to 20 years. Metabolic volumetric products of the parotid, submandibular, and thyroid gland were calculated and analyzed with increasing age in subjects who underwent PET/CT imaging. Structures that exhibited statistically significant changes (P < 0.05) with increasing age included the submandibular glands, thyroid gland, soft palate, and adenoids. The CT volume of the submandibular glands increased with age, and the attenuation decreased with age with statistical significance. The thyroid gland volume, as measured using MRI, showed a statistically significant decrease with aging. The volume of the soft palate and lingual tonsils, as measured by MRI, exhibited a statistically significant decrease in volume with aging. The maximum SUV of the adenoids demonstrated a statistically significant decrease with aging. In conclusion, CT, MRI, and PET may be used to quantitatively and qualitatively assess structures of the head and neck and are useful in the assessment of structural and functional changes of these structures with aging.

The institutional review board approved the described HIPAA-compliant study, which was performed to prospectively evaluate observer performance in the detection of artificial multiple sclerosis (MS) lesions that were randomly distributed supra- and infratentorially on simulated fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) images obtained at different echo times (TEs). MR parametric maps were derived from mixed multi-echo inversion-recovery images obtained in a 40-year-old healthy male volunteer and in a patient with MS, both of whom gave informed consent. Pseudo-randomly distributed artificial MS lesions of varying size, number, and location were equally represented on the FLAIR images (11 000/100-200/2600 [repetition time msec/TE msec/inversion time msec]). Twelve images obtained in both regions at each of 11 TEs spaced 10 msec apart were rated by seven neuroradiologists by using a four-point scale. Observer performance in the detection of MS lesions on the FLAIR images, as estimated by using areas under the alternative free-response receiver operating characteristic curve, was highest and most consistent at the 100-msec TE, both supratentorially (93.0% +/- 8.6 [standard error of the mean]) and infratentorially (87.4% +/- 10.0).

In this work, the feasibility of using T2ρ weighting as an MR contrast mechanism is evaluated. Axial images of a human brain were acquired using a single-slice spin-lock T2ρ-weighted pulse sequence and compared to analogous T2-weighted images of the same slice. The contrast between white matter and gray matter in T2ρ-weighted images was approximately 40% greater than that from T2-weighted data. These preliminary data suggest that the novel contrast mechanism of T2ρ can be used to yield high-contrast T2-like images. Magn Reson Med 52:1223–1227, 2004. © 2004 Wiley-Liss, Inc.

Objective: To present magnetic resonance imaging (MRI) findings of Wallerian degeneration after diffuse axonal injury (DAI). Material and methods: A 20-year-old unrestrained driver sustained a motor vehicle accident with DAI. A follow-up MRI revealed findings suggestive of Wallerian degeneration. Results: Wallerian degeneration is demonstrated on MRI after DAI. Conclusion: We present this case and review the literature.

The early detection and specific diagnosis of viral infections of the central nervous system are important because many of these diseases are potentially treatable. However, clinical symptoms and physical examination are often nonspecific, and rapid diagnostic tests are available for some, but not all, viruses. Neuroimaging, in conjunction with clinical history and laboratory tests, plays an important role in narrowing the differential diagnoses. In this article, we review the clinical features, imaging characteristics, diagnosis, and treatment of the more common viral infections and prions that involve the central nervous system.

From a clinical-radiologic standpoint, there are a limited number of structures and disease entities in the temporal bone with which one must be familiar in order to proficiently interpret a computed tomographic or magnetic resonance imaging study of the temporal bone. It is helpful to examine the region in an organized and systematic fashion, going through the same checklist of key structures each time. This is the first of a two-part review that provides a practical approach to understanding temporal bone anatomy, localizing a pathologic process with a focus on inflammatory and neoplastic processes, identifying pertinent positives and negatives, and formulating a differential diagnosis.

Purpose To compare objective and subjective image quality in neck CT images acquired at different tube current–time products (275 mA s and 340 mA s) and reconstructed with filtered-back-projection (FBP) and adaptive statistical iterative reconstruction (ASIR). Materials and methods HIPAA-compliant study with IRB approval and waiver of informed consent. 66 consecutive patients were randomly assigned to undergo contrast-enhanced neck CT at a standard tube-current–time-product (340 mA s; n = 33) or reduced tube-current–time-product (275 mA s, n = 33). Data sets were reconstructed with FBP and 2 levels (30%, 40%) of ASIR-FBP blending at 340 mA s and 275 mA s. Two neuroradiologists assessed subjective image quality in a blinded and randomized manner. Volume CT dose index (CTDIvol), dose-length-product (DLP), effective dose, and objective image noise were recorded. Signal-to-noise ratio (SNR) was computed as mean attenuation in a region of interest in the sternocleidomastoid muscle divided by image noise. Results Compared with FBP, ASIR resulted in a reduction of image noise at both 340 mA s and 275 mA s. Reduction of tube current from 340 mA s to 275 mA s resulted in an increase in mean objective image noise (p = 0.02) and a decrease in SNR (p = 0.03) when images were reconstructed with FBP. However, when the 275 mA s images were reconstructed using ASIR, the mean objective image noise and SNR were similar to those of the standard 340 mA s CT images reconstructed with FBP (p > 0.05). Subjective image noise was ranked by both raters as either average or less-than-average irrespective of the tube current and iterative reconstruction technique. Conclusion Adapting ASIR into neck CT protocols reduced effective dose by 17% without compromising image quality.

High-pitch CT angiography (CTA) is a recent innovation that allows significant shortening of scan time with volume coverage of 43 mm per second. The aim of our study was to assess this technique in CTA of the head and neck.CTA of supra-aortic arteries was performed in 50 patients using two acquisition protocols: conventional single-source 64-slice (pitch 1.2) and high-pitch dual-source 128-slice CT (pitch 3.2). Subjective and objective image quality of supra-aortic vessel ostia as well as intra- and extra-cranial segments was retrospectively assessed by blinded readers and radiation dose compared between the two protocols.Conventional and high-pitch CTA achieved comparable signal-to-noise ratios in arterial (54.3 ± 16.5 versus 57.3 ± 14.8; p = 0.50) and venous segments (15.8 ± 6.7 versus 18.9 ± 8.9; p = 0.21). High-pitch scanning was, however, associated with sharper delineation of vessel contours and image quality significantly improved at the level of supra-aortic vessel ostia (p0.0001) as well as along the brachiocephalic trunk (p0.0001), the subclavian arteries (p0.0001), proximal common carotid arteries (p = 0.01), and vertebral V1 segments (p0.0001). Using the high-pitch mode, the dose-length product was reduced by about 35% (218.2 ± 30 versus 141.8 ± 20 mGy × cm).Due to elimination of transmitted cardiac motion, high-pitch CTA of the neck improves image quality in the proximity of the aortic arch while significantly lowering radiation dose. The technique thus qualifies as a promising alternative to conventional spiral CTA and may be particularly useful for identification of ostial stenosis.

Perineural tumor spread (PNS) is a mode of neoplastic spread whereby tumor cells use neural conduits to escape the borders of a primary tumor. MRI is generally favored over CT for evaluating PNS, and findings include obliteration of fat within skull base foramina, enlargement and enhancement of the involved nerves, and enlargement and destruction of the bony foramina. Careful examination of the entire course of the nerve allows detection of skip lesions. Recognition of the complete extent of PNS is crucial for correct treatment because it facilitates both surgical and radiotherapy targeting of entire extent of disease.